Pregnancy testing of various types for human beings and for animals is of considerable interest and many different types of tests are known.
Some of the methods are biological in nature and require the use of a specific animal, for example rabbits, mice, frogs, etc. These biological tests have serious drawbacks, for example in requiring the availability and housing of many animals which meets specific requirements. Tests of this type are consequently rather complicated and expensive, also requiring special laboratory techniques and considerable time for arriving at a result. The time required may be several days.
Improvements in testing for pregnancy have been provided which overcome many of these drawbacks, for example tests which do not require special animals or special laboratory techniques. Attempts have also been made to provide tests which can be performed in a physician's office and which can give the desired result within a relatively short time.
Israel Pat. No. 16245 describes serodiagnostic compositions for the diagnosis of pregnancy comprising chorionic gonadotropin hormone combined with sheep red blood cells by means of bis-diazo-benzidine and chorionic gonadotropin hormone antibody. However, these compositions are unsatisfactory from the standpoint of stability. Attempts to overcome this drawback by the addition of formaline, a stabilizing agent, have not been satisfactory because the storage period of the resulting composition was still too short, particularly if resuspended in liquid, and this is a serious drawback.
Attempts have also been made to reduce the time required for the pregnancy determination tests. However, the time in general was always measured in hours, generally in about two hours, rather than in minutes.